1. Field of the Invention
The present invention is generally related to communication systems. More particularly, the present invention is related to cable modem systems and methods for creating DOCSIS headers.
2. Related Art
Conventional cable modem systems utilize DOCSIS (Data Over Cable System Interface Specification)—compliant equipment and protocols to transfer data between one or more cable modems (CM) and a cable modem termination system (CMTS). DOCSIS generally refers to a group of specifications that define industry standards for cable headend and cable modem equipment. In part, DOCSIS sets forth requirements and objectives for various aspects of cable modem systems including operations support systems, management, data interfaces, as well as network layer, data link layer, and physical layer transport for cable modem systems. The most current version of the DOCSIS specification is DOCSIS 1.1.
In accordance with the DOCSIS specification, a media access control frame (MAC) is applied to each data packet transmitted and is used to convey information about the data packet as it is passed through the system from one component to the next. As shown in FIG. 5, the MAC frame includes a DOCSIS header portion and an optional Data PDU portion. The DOCSIS header identifies the contents of the MAC frame and contains information for directing the data packets to the proper location in the cable modem system. The Data PDU portion contains the payload data such as voice or text data for example. The DOCSIS header also provides data format information related to the PDU (payload) portion.
Heretofore, cable modems and cable modem termination systems have relied upon the host processor system and software to generate the DOCSIS header. Reliance upon software, however, results in significant processing overhead. Thus, what is needed is an apparatus and method for creating DOCSIS headers in hardware such that the performance of the overall system is improved.